Inside and Outside Carlsbad Caverns

Imagine watching hundreds of thousands of bats swirl around you, swarming to form a large, black mass that flies off into the horizon. At Carlsbad Caverns in New Mexico, this scene is a regular occurrence. The caverns, located in a United States National Park, are home to around 400,000 Mexican free-tailed bats that fly out into the night sky each evening at dusk to feed on nearby moths and insects, returning at dawn to their caves. The spectacle draws crowds from around the world into the Chihuahuan Desert, where the park is located. One such visitor was Laurel Mathews, who once visited the caves with her family on a road trip.

“At the entrance to one of the caves, there’s stadium seating for visitors to watch the bats,” she remembers. “We waited a long time to see them. Finally, they started circling out of the cave and they flew off—out came more and more and more, all of them flying in loops and then out into the sky. It was amazing that there were so many!”

Laurel also remembers the sound the bats made, describing the high, screeching noise. “It was really creepy, but also really cool,” she says.

Laurel recalls her family’s arrival at the Carlsbad Caverns National Park. “It didn’t look very spectacular when we first drove in,” she admits. “But then we started exploring the big network of underground caves.”

The formation of the caves is a result of a fossilized reef that existed 250 to 280 million years ago in an inland sea that has long since disappeared. Since limestone is typically made up of fragments of coral, a large limestone deposit eventually formed in the area. Today, you can still find several fossilized plants and animals in the caves’ limestone that date back to a time before dinosaurs walked the earth. Starting sometime between four and six million years ago, water from the earth’s surface began moving through the cracks in the stone deposit. There is a type of acid in surface water. When this water combined with rainwater, the two mixed to form another type of acid as a result of their chemical compositions. This acid slowly dissolved the limestone to eventually form the winding caves that exist today in Carlsbad Caverns. This is a very common process that happens to limestone—many caves all around the world exist in limestone deposits due to the stone’s solubility (the ability of a substance to be dissolved) in a mixture of water and acid.

Eventually, speleothems—formations that arise from mineral deposits in caves—began to take shape in the lower levels of the caverns. In fact, these speleothems existed during the last ice age, when instead of a desert, a pine forest sat above the caves. Over the years, park employees and rangers have found clues that hint at the caves’ history. For example, according to the National Park Service, people have found some bones of ancient ice age animals scattered around the entrance to some of the caves. In 2003, an employee found a part of a stone scraper dating back to the last ice age near a cave entrance as well. Clearly, the caves have a long history—researchers have discovered that Native Americans first inhabited the area sometime between 12,000 and 14,000 years ago. Ever since then, the caves have been explored by several groups, including Spanish explorers in the 1500s, and later by other explorers and guides who drew attention from all across the country to the natural phenomenon.

Laurel remembers this phenomenon very well. “It took us between one and two hours to get all the way to the bottom,” she says, recounting the windy pathway leading deeper and deeper into the heart of the caves. “The park had put in blue and red lights to highlight the beautiful rock formations.”

Once they reached the bottom, Laurel says that she had to take an elevator to get back to the top. “My ears popped so much in the elevator!” she remembers. “It took a really long time to reach the top; I didn’t realize how far down we were until we were on our way back up.”

Creepy Cave Crawlers

Cave creatures discovered in California hold clues to monitoring changes in the environment.

Inside the dark, damp underground caves of two national parks in central California, scientists made an amazing discovery. They found 27 previously unknown species of spiders, centipedes, millipedes, and scorpion-like creatures. The scientists explored 34 of 238 known caves in Sequoia and Kings Canyon national parks between 2002 and 2005.

The cave dwellers are all invertebrates, or animals without backbones. The discoveries included a tiny pill bug that is translucent, or almost clear. Its internal organs are visible—even its bright-yellow liver! There was also a daddy-longlegs with a jaw larger than its body, as well as a little, bright-orange spider. Some creatures were so tiny that scientists had to use the fine hairs of a paintbrush to collect them.

"We thought we might find a handful of new species," said Joel Despain, a cave expert for the parks. "It was amazing to find 27."

Cool Cave Mysteries

Why had the cave creatures gone undetected? Though it is rare to find unknown animal species on Earth’s surface, the same is not true for caves. Like the deep sea, many caves are difficult to reach and haven’t been explored as thoroughly as the Earth’s surface.

Discovering so many unknown species was thrilling for Jean Krejca. She is a scientist with Zara Environmental, the Texas-based group that led the project. "You get the feeling that you’re Lewis and Clark charting undiscovered territory," Krejca said. "Caves are one of the last frontiers."

Adapting to Cave Life

The creatures are unique, not only because they are found just in caves, but also because some are found in only a single cave or a specific part of a cave.

"There are usually more creatures at the cave’s entrance because there is more food there," scientist Rob Myers of Zara Environmental told Weekly Reader. "The farther back in a cave, the more you find creatures have adapted to cave life. What you find is more and more strange. The creatures are often blind and have no pigment." Pigment is a substance that gives color.

A creature such as the pill bug, for example, doesn’t need pigment in its skin, because it doesn’t have to protect itself from the sun. And the daddy-longlegs probably developed such big jaws to quickly grab prey, which is scarce inside caves.

Classifying the Creatures

Whenever a new species is discovered, the next task is to name the species. Specialists called taxonomists work to classify and name newly discovered creatures.

Certain scientists also study the new species to determine whether their populations are healthy. Cave animals can teach scientists a lot about the environment because the creatures are sensitive to changes in the ecosystem. An ecosystem is a community of plants and animals that interacts with the environment. If cave creatures decline, it could signal problems or changes in the environment.

The discoveries in the early 2000s led park officials to plan to protect the caves and the newly found species. "Now that we know the species are there, we can use them to learn more about cave ecosystems and life on this planet," said Myers.

Exploring Caves

What do you call someone who explores and studies caves? A spelunker!

"Caves are absolutely dark," Rob Myers of Zara Environmental told Weekly Reader. "They are darker than your bedroom gets at night. There is zero light in a cave, so you can’t see a hand in front of your face."

When spelunkers head into caves, they wear a helmet with a headlamp and carry an extra flashlight. Cave explorers also wear elbow pads and kneepads to crawl along the rocky floor. Many caves are underground, so the explorers slide down on ropes connected to special harnesses.

While there, a spelunker might see the magnificent cone-shaped formations of stalagmites (stuh-LAG-mights) and stalactites (stuh-LAK-tights). They form when water with calcium drips, and the mineral hardens and builds up over time.

Stalagmites rise from the ground. Stalactites resemble icicles and hang from a cave’s ceiling. When they meet, they form a column. What is an easy way to remember the difference between the words? Stalactite has a c for ceiling, and stalagmite has a g for ground.